Physics Electrostatics KU 2024
PMDC Verified Question 9 of 131
Q.186 According to Coulomb's law, what happens to the electrostatic force between the 2-point charges if the distance between them is doubled?
A
The force becomes one-fourth
B
The force becomes half
C
The force doubles
D
The force remains the same
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: The force becomes one-fourth
1. Concept:

Moving charges further apart weakens their mutual electrostatic interaction following the inverse square law.

2. Formula:

$$ F \propto \frac{1}{r^2} $$

3. Solution:

  • Let the new distance be \( r' = 2r \).


  • Plug it into the proportion: \( F' \propto \frac{1}{(2r)^2} \).


  • Square the coefficient: \( F' \propto \frac{1}{4r^2} \).


  • The result is \( \frac{1}{4} \) of the original mathematical expression, proving the force drops to one-fourth.


4. Why other options are incorrect:

Option B assumes a linear \( 1/r \) drop-off. Option C falsely assumes force increases with distance. Option D assumes force is completely independent of distance.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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